Big Bang—The Evolution of a Theory

When it was first introduced, the “big bang” was sometimes an object of ridicule. But over the past decades, it has proven to be quite pliable, morphing to adapt to each new problem. Are these changes true improvements, or just rescuing devices?

We frequently hear in creationist circles that the big bang model is fraught
with problems and is a theory in crisis. However, as Mark Twain reported about
his death, its demise may be greatly exaggerated. But not for the reasons that
you might think.

The big bang had little traction when it was first introduced, but a breakthrough
came in 1964, when astronomers discovered the cosmic microwave background. The
big bang model had predicted this microwave background, but the competing model
(the “steady state” theory) had not. This background radiation supposedly comes
from a period of time a few hundred thousand years after the big bang when the
universe was still hot.

So the big bang quickly became the dominant theory of the history of the universe
among cosmologists. Since then new observations and ideas have come along that
have challenged the big bang. Rather than abandoning the theory, however, cosmologists
and astronomers have met each challenge with modifications. In the process,
the big bang has morphed into something that little resembles its first incarnation.
Many people view these modifications as improvements, but are they really?

The Horizon Problem—Is Inflation the Answer?

Despite its supposed proof of the big bang, the cosmic microwave background
has been a source of challenges to the standard cosmology. One difficulty is
the horizon problem. No one expects that a big bang universe would have started
with exactly the same temperature everywhere. If you look out into the universe
in one direction, for example, due east, you will receive radiation from a distant
region (call it region A) that secular astronomers say is just now reaching
earth after traveling for more than 13 billion years, the supposed age of the
universe. If you look in the opposite direction, for example, due west, you
will see radiation that is just arriving from another location (call it region
B). We find that the radiation from points A and B reveals that these regions
have almost precisely the same temperature. But that shouldn’t be if the two
regions haven’t yet had time to exchange energy and equalize their temperatures.

These points couldn’t yet have been in “thermal contact” with one another since
they are 26 billion light years apart, so why do they have the same temperature?
This question arises regardless of which direction we look.

About thirty years ago cosmologists attempted to resolve this problem with
inflation. In cosmology, inflation is a hypothetical hyper-expansion (far greater
than the speed of light) that occurred very early in the universe.1 This means the pre-inflation universe would have been incredibly
small, and the entire universe could have been in thermal contact with itself.
That would explain why the early universe reached the same temperature throughout.

Flatness Problem—Is Inflation the Answer?

Inflation also was invoked to explain another difficulty, the flatness problem.
As the universe expands, the ratio of gravitational potential energy to kinetic
energy (denoted by the Greek letter omega) changes. After billions of years
of expansion, the ratio ought to be either almost exactly zero or a very large
number. However, measurements have shown that the ratio is only slightly below
1. In the big bang cosmology this suggests that the value of omega initially
was almost exactly 1, as opposed to an infinite number of other possibilities.
This makes the universe seem very improbable.

So inflation is their rescuing device. If they assume inflation occurred in
the early universe, it would have driven the value up to almost exactly 1, where
it needed to be, and from that point it could have decreased only slightly,
even after billions of years. There is no independent evidence that inflation
indeed happened—outside of their need for it to happen. But astronomers almost
universally accept that it did because otherwise they have no other way to solve
the horizon and flatness problems.

Smoothness Problem—Solved by Revising the Theory?

Another problem with cosmic background radiation is that it is almost perfectly
smooth. Today we see hierarchal structure in the universe, with matter clumped
into stars that in turn are clumped into galaxies and clusters of galaxies.
In short, the universe is clumpy, not smooth.

To explain this clumpy structure, cosmologists require that the matter in the
early universe not be perfectly smooth (homogeneous) but instead have regions
that were slightly denser, interspersed with regions that were less dense (an
inhomogeneous universe). The denser regions supposedly acted as gravitational
seeds that attracted surrounding material to produce the structure that we see
today.

Unfortunately for their theory, these inhomogeneities must have been fine-tuned,
not too small and not too great. If the early universe were too smooth, the
structures that we see today wouldn’t be here (nor would we). But if the inhomogeneities
were too great, nearly all matter would have transformed into massive black
holes, and again the structures that we see today wouldn’t be here (nor would
we). This sort of fine-tuning is required only in a universe that came from
a big bang billions of years ago, not if the universe was created in six normal
days as Genesis 1 states.

These required inhomogeneities would also have left their imprint upon the
cosmic radiation background as slight temperature differences. Cosmologists
predicted what the temperature differences ought to be, about 1 part in 10,000.
More than two decades ago they designed the COBE (Cosmic Background Explorer)
spacecraft to measure these temperature differences, but the finding was perfectly
smooth cosmic background.

Only after very meticulous data manipulation did scientists find evidence of
temperature differences in the background radiation, but on a much smaller level
than predicted and beyond the detection ability of the probe (one part in 100,000).
This was later confirmed by more sensitive studies, such as the WMAP (Wilkinson
Microwave Anisotropy Probe) mission a decade ago and the Planck mission just
this year.

Yet many scientists now claim that the predictions of the theory beautifully
matched the data. How can they say that? After the theory failed to correctly
predict the data, cosmologists altered the details of the theory to match the
data.

Need for a Faster Expansion Rate—So Reevaluate the Old Data?

Another challenge came two decades ago when astronomers decided new observations
required that they increase their measure of the expansion rate of the universe.
A faster expansion rate results in a younger age of the universe. Since about
1960, astronomers had thought that the universe was 16–18 billion years old,
but now astronomers think that the universe actually is 13.8 billion years old.
This was a huge problem, because for many years astronomers thought that globular
star clusters were at least 15 billion years old, making them more than a billion
years older than the universe.

Astronomers eventually resolved this problem by reevaluating the distances
of globular star clusters. The revised distance estimates led to more accurate
assessments of inherent brightness, which affects the secular estimations of
age.

The Cosmological Constant—Blunder or Reality?

Nearly a century ago Albert Einstein produced a model of the universe based
upon his general theory of relativity, but it had a serious problem. It did
not produce a nonexpanding, static universe as he expected. Without some force
to counteract the effects of gravity, the universe would collapse in on itself.

So Einstein inserted something he called “the cosmological constant” to make
his model match how he thought the universe ought to operate. Essentially the
cosmological constant is the repulsion that space has for itself. By choosing
the right value for the cosmological constant, Einstein believed this repulsive
force of space would exactly balance the attractive force of gravity, leading
to a static universe.

When new evidence indicated that the universe may not be static after all,
he quickly abandoned the cosmological constant, calling it the greatest blunder
he ever made. This paved the way for the big bang model, which generally did
not make allowance for this effect.

However, Einstein was too harsh on himself; for in 1998 and 1999 astronomers
obtained data that they believe indicates that something is causing the universe’s
rate of expansion to increase. The brightness of type Ia supernovae at extreme
distance does not match what we would expect for their distance, assuming a
constant expansion rate. Dark energy has been invoked as the explanation for
this strange effect. Dark energy is slightly different from the cosmological
constant because its repulsion varies over time, while the cosmological constant
doesn’t vary. We don’t yet know which of these is correct, or if there is some
other explanation for the unexpected luminosity-redshift relation for distant
type Ia supernovae. So the big bang model had to adapt to yet another new discovery.
Who knows what will be next?

Indeed, speaking of things dark, since the 1930s there has been growing evidence
that much of the matter in the universe is dark. That is, the majority of the
mass in the universe gives off no light or any other detectable radiation, suggesting
some strange form of matter that we don’t yet know about. It was many years
before cosmologists took this seriously, so only in recent years have astronomers
begun to include the treatment of dark matter in their theories, including the
big bang theory.

The Latest Wrinkle—String Theory

Finally, string theory is a new idea that theoretical physicists have developed
to explain other mysteries about how matter works, especially subatomic physics.
Certain properties of elementary particles can be best explained if the universe
has at least six additional spatial dimensions, dimensions that we normally
cannot detect. There is no evidence for this, so it probably is better to call
this the string hypothesis rather than string theory.

If this hypothesis is true, then scientists ought to include it in their treatments
of the early big bang universe. So in recent years cosmologists have begun to
include string theory in their models.

It’s instructive to compare today’s big bang model with the model just thirty
years ago. Back then the estimated expansion rate, and hence the assumed age
of the universe, was very different from today. Back then no models included
inflation, but today one would not think of omitting it. The same is true of
dark matter, dark energy, and string theory. In short, the big bang model of
today bears almost no resemblance to the model of thirty years ago.

What will the big bang model be like thirty years from now? If history is any
indicator, two things are certain. First, the model in thirty years will be
very different from the model today. Second, scientists then, as today and thirty
years ago, will have complete confidence that the model is correct, even if
all three contradict one another.

A theory that can explain anything and everything,
no matter how contradictory, really isn’t science.

Many scientists today think that the big bang model is very successful in that
it can explain all sorts of new observations and problems. But it does this
by the endless addition of rescuing devices. If a scientific theory can be freely
amended to account for any new challenges, then can the theory ever be proved
wrong? In science it’s important that an idea be able to be proved wrong, at
least hypothetically. A theory that can explain anything and everything, no matter how contradictory,
really isn’t science.

Another Epicycle?

The life cycle of the big bang theory has an interesting parallel to an earlier
(in)famous theory. In the second century AD Claudius Ptolemy developed his cosmological
theory to explain the complex motions of the sun, moon, and planets. The Ptolemaic
model required a series of circles upon circles called epicycles. Ptolemy found
that by adjusting the sizes of the circles and the speeds of the motions, he
could produce a good fit to the data.

This theory proved to be very successful in that it was widely believed for
15 centuries. In terms of longevity, no other theory in science even comes close
to such success. Over the centuries, some discrepancies between the theory and
observations arose, but people found that they could fix the problems by adjusting
the theory with the addition of more epicycles. By the end of the Middle Ages
some versions of the Ptolemaic model required a hundred or more epicycles.

While this feature of endless modification was the reason for the success of
the Ptolemaic theory, it eventually was its undoing, because the theory was
abandoned largely over its complicated and unwieldy nature. The continued modification
of the big bang model is beginning to resemble this cycle. How long will it
last?

Not Your Father’s Big Bang Theory

When we hear the term big bang theory, many people assume it was conceived
in its present form and has remained unassailed ever since. In reality, it
is a very pliable model. Several assumed variables in the equations have been
changed to make the numbers match new findings. Today’s big bang model little
resembles the one your grandfather learned, and it is likely to continue morphing.
Are these improvements, or just rescuing devices?

Dr. Danny Faulkner joined the staff of Answers in Genesis
after 26 years as professor of physics and astronomy at
the University of South Carolina Lancaster. He has written
numerous articles in astronomical journals, and he is the
author of Universe by Design.

Answers Magazine

October – December 2013

With an updated interior design, the fall issue has it all, from breaking down the big bang to building a better understanding of dinosaurs, from public schools to pinnipeds, and from archaeological discoveries at Çatalhöyük to the astronomical delight of a Christmas comet.

Risk-free trial issue!

First name:

Last name:

Email:

Address:

Address2:

City:

State:

Zip:

Leave unfilled:

If you decide you want to keep Answers coming, simply pay your invoice for just $24 and receive four issues (a full year) more. If not, write “cancel” across the invoice and return it. The trial issue is yours to keep, regardless!

Please allow 4-6 weeks for delivery.
New subscribers only. No gift subscriptions.Offer valid in U.S. only.

Footnotes

Contrary
to popular misconception, this does not violate general relativity. While objects
may not move faster than light, space can expand more rapidly than the speed
of light.

Newsletter

Thank You!

Thank you for signing up to receive email newsletters from Answers in Genesis.

Whoops!

Your newsletter signup did not work out. Please refresh the page and try again.

Answers in Genesis is an apologetics ministry, dedicated to helping Christians defend their faith and proclaim the gospel of Jesus Christ effectively. We focus on providing answers to questions about the Bible—particularly the book of Genesis—regarding key issues such as creation, evolution, science, and the age of the earth.